PROJECT SUMMARY/ABSTRACT Digital breast tomosynthesis (DBT) has been shown to significantly increase accuracy in the early detection and diagnosis of breast cancer. The goals of this proposal are to further enhance the efficacy and performance of this type of imaging by removing mechanical motion of the X-ray tube through the development of a stationary X-ray source DBT system. The development of a stationary X-ray source DBT system will enable a 3- to over 10-fold decrease in scan time relative to that of existing commercial systems. Shorter scan times improve image quality by reducing instances of patient motion without introducing image blurring due to tube movement or vibration ? keys to exploiting the improved imaging sensitivity of DBT. In addition, it is anticipated that the proposed system could expand the availability of DBT by decreasing up-front capital, operating, and maintenance costs. We expect that lower-cost, higher-performance imaging will accelerate the on-going displacement of full-field digital mammography by DBT, thereby providing more women with higher quality imaging sooner.